1. Field of Invention
The present invention relates to a testing device, which uses a microchip to identify the component to be detected to measure the concentration of the component to be detected in the liquid sample of the object to be measured by absorbance determination. More specifically, this invention relates to a testing device used to measure the activity of the enzymes necessary to diagnose human liver function, such as GPT (glutamate pyruvate transaminase) and γ-GTP (γ-glutamyltranspeptidase).
2. Description of Related Art
The analysis method adapting micro-machine technology, which uses p-TAS (μ-Total Analysis System) and which performs more refined chemical analysis as compared to the conventional devices, and a microchip called “Lab on a chip,” has attracted attention in recent years. Such technology is disclosed in Japanese published unexamined application 2007-225479. Analysis using such microchips aims to perform all analyzing processes, such as mixing, reaction, separation, extraction, and detection of the reagents, in micro-channels formed on a small substrate using micro-machine production technology. For example, this system is used in blood analysis and biomolecular analyses, such as the analysis of ultra-trace amounts of protein and nucleic acids, in the medical field.
The absorption photometry is frequently used to determine the quantity of the extracts or reactive organisms in the device using μ-TAS (referred to as the “testing device” hereinafter). The microchip is structured such that the samples to be tested and reagents to detect the information of the aforementioned test sample are contained in separate sites and the test fluid obtained by mixing test sample and reagent is filled in a very small test fluid receiver having a cross section φ of about 0.01 to 5 mm2. In the actual analysis, light having a wavelength, which is absorbed by the test fluid, is emitted into the test fluid receiver and the amount of the light absorbed by the test fluid is measured to detect the concentration of the component of the test sample.
Ideally, lasers may be used since a discharge lamp of the testing device must emit light with high parallelism into the microchip test fluid receiver. However, it is necessary to use light with different wave lengths for the analysis of different test samples. Therefore, when only one device is intended to be used to analyze more than one sample, it is necessary to provide different types of lasers having specific wave lengths according to the types of the samples. This may cause some disadvantages, such as the increase in the size of the device as well as the increase of the cost. On the other hand, when a continuous light emitting lamp, such as a xenon lamp, is used as the discharge lamp along with a wavelength selecting device, the above mentioned disadvantages, such as the increase in the size of the device and the increase of the cost, can be avoided, since light with different wavelengths can be selected according to each sample.
Also in recent years, the POCT (Point of Care Testing), which conducts quick and highly precise analysis, is frequently performed in the clinical settings, such as in hospitals or clinics, emergency spots, and at home. In order to perform the POCT using the above mentioned testing device, it is required that the testing device be compact/simple and an easy to handle unit, since it is carried to the site where the diagnosis is to be performed. In addition, when the testing device adapting the μ-TAS is used, it is required that the intensity of the light emitted from the discharge lamp be high, since the light emitted from the discharge lamp must be lead to the narrow light path to reach into the microchip test fluid receiver. In other words, measurement errors can be minimized by increasing the intensity of the light emitted into the test fluid container unit. Based on these conditions, it is necessary that the brightness of the discharge lamp used in the testing device be high.
However, when the intensity of the light emitted form the discharge lamp is increased, the electromagnetic waves emitted around the discharge lamp may become so large as to cause malfunctioning of the precision apparatus of the testing device, and accurate analysis cannot be performed, especially when the rated wattage is raised to increase the brightness of the discharge lamp as described above; it becomes clear that adverse effects of the electromagnetic waves generated around the discharge lamp on the precision apparatus will increase and there will be higher chances of malfunction of the precision apparatus.
Installation of a shielding board between the image processing device and the discharge lamp in order to control the influence of the electromagnetic waves, which are emitted around the discharge lamp of the endoscopical device, on the precision apparatus is disclosed in Japanese published unexamined application 2005-245473. However, it is required to simplify and to reduce the size of the testing device used in the POCT as described above. Therefore, it is not desirable to adapt the technology described in Japanese published unexamined application 2005-245473, since it opposes these requirements.